1. Technical Field
The present disclosure relates to surface light source devices and, particularly, to a surface light source device employing double prism sheets.
2. Description of Related Art
With the advantages of long service life, low pollution, and energy efficiency, light-emitting diodes have been widely used in lighting devices. The light-emitting diode is a point light source with a small radiation angle. A plurality of light-emitting diodes distributed in rows on the lighting device is usually needed to obtain a large lighting surface. However, the high brightness light-emitting diodes always cause light spots on the lighting surface of the lighting device. An extra light diffusion film is needed to reduce or eliminate the light spots and achieve a uniform lighting surface. However, the light diffusion film may absorb part of the light from the light-emitting diodes. Thus, the brightness of light illumination of the lighting device is reduced.
Therefore, what is needed is a surface light source device to overcome the above-mentioned shortcomings.